CN Mobile Logo

Search form


Iodine I 131 Tositumomab for Patients With Follicular Non-Hodgkin’s Lymphoma (NHL): Overall Clinical Trial Experience by Histology

Iodine I 131 Tositumomab for Patients With Follicular Non-Hodgkin’s Lymphoma (NHL): Overall Clinical Trial Experience by Histology


Iodine-131 tositumomab (Bexxar) is a new radioimmunotherapy in development for the treatment of patients with low-grade or transformed low-grade non-Hodgkin’s lymphoma. The data from five phase I-III studies, which enrolled patients with low-grade NHL or transformed low-grade NHL, were analyzed.

This analysis focuses on 179 patients with follicular small cleaved cell (FSCL) or follicular mixed cell with > 50% small cleaved cell (FML) histology at the time of treatment with tositumomab. Patients had received a median of 2 (range, 0 to 13) prior chemotherapy regimens, and 64 (49%) of 124 patients had failed to respond to their last chemotherapy regimen. The median duration of response to the last chemotherapy regimen was 6 months. Baseline patient characteristics were: median age, 52 years; 107 patients were male; median time from diagnosis to entry was 29 months; 38% of patients had elevated lactic dehydrogenase (LDH); 58% of patients had a positive baseline bone marrow biopsy (< 25% lymphoma).

Patients generally received a single dosimetric dose (450 mg of tositumomab intravenously [IV] followed by 35 mg of tositumomab radiolabeled with 5 mCi of iodine-131 over ½ hour) and then had three whole-body counts obtained over the next 7 days. The whole-body counts were used to calculate the required activity (mCi) to deliver the desired therapeutic dose (65 cGy for platelet counts of 100,000 to 149,999 cells/mm³ and 75 cGy for platelet counts ³ 150,000 cells/mm³). A single therapeutic dose (450 mg of tositumomab antibody IV followed by 35 mg of tositumomab containing an appropriate activity [mCi] of iodine-131 to deliver the specified total-body dose [cGy] over ½ hour) was administered 7 to 14 days after the dosimetric dose.

An overall response (complete and partial) was observed in 145 (81%) patients, and 69 (39%) patients had a complete response (CR). The median duration of response was 11 months (95% confidence interval [CI], 9 to 16 months), and median time to progression (TTP) for responders was 13 months (95% CI, 11 to 19 months). The median duration of CR was 57 months (95% CI, 31 months to not reached). Overall response by histology was: FSCL, 91 (83%) of 110 patients (38% CRs); and FML, 54 (78%) of 69 patients (39% CRs).

The principal toxicity was hematologic: absolute neutrophil count (ANC) was < 500 cells/mm³ in 17% of patients, and platelet count was < 10,000 cells/mm³in 3%. The hematologic nadir typically occurred at week 5 to 6, with recovery by week 8 to 9. Transient, mild to moderate nonhematologic toxicity occurred, with the most frequent events being fatigue (39%), fever (37%), and nausea (36%). Human antimurine antibodies developed in 12% of previously treated patients. Median survival from study entry was 74 months (95% CI, 36 months to not reached).

CONCLUSIONS: These results demonstrate that tositumomab is a safe and effective therapy for the treatment of patients with follicular NHL.

Click here for Dr. Bruce Cheson’s commentary on this abstract.

Loading comments...

By clicking Accept, you agree to become a member of the UBM Medica Community.